U.S. patent number 6,705,103 [Application Number 10/168,914] was granted by the patent office on 2004-03-16 for device and method for cooling.
This patent grant is currently assigned to Robert Bosch GmbH. Invention is credited to Stephan Leuthner.
United States Patent |
6,705,103 |
Leuthner |
March 16, 2004 |
Device and method for cooling
Abstract
The invention relates to an apparatus for cooling, having a loop
(60) carrying a refrigerant, a first heat exchanger (10) for
outputting heat to a heat reservoir (12), a second heat exchanger
(114) for extracting heat from a chamber (116) to be cooled, a
compressor (18) and an expansion device (120), wherein in that a
first further heat exchanger (70) is provided, which enables a heat
transfer between the loop (60) carrying the refrigerant and a
coolant loop (80). The invention also relates to a method for
cooling.
Inventors: |
Leuthner; Stephan (Stuttgart,
DE) |
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
7668974 |
Appl.
No.: |
10/168,914 |
Filed: |
June 24, 2002 |
PCT
Filed: |
September 25, 2001 |
PCT No.: |
PCT/DE01/03692 |
PCT
Pub. No.: |
WO02/05220 |
PCT
Pub. Date: |
July 04, 2002 |
Foreign Application Priority Data
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Dec 23, 2000 [DE] |
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100 65 002 |
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Current U.S.
Class: |
62/238.6;
62/323.1 |
Current CPC
Class: |
F25B
9/008 (20130101); F25B 40/04 (20130101); B60H
1/00007 (20130101); F25B 27/00 (20130101); B60H
1/00314 (20130101); B60H 1/3204 (20130101); F25B
2309/061 (20130101); F25B 40/00 (20130101) |
Current International
Class: |
B60H
1/00 (20060101); B60H 1/32 (20060101); F25B
9/00 (20060101); F25B 40/04 (20060101); F25B
27/00 (20060101); F25B 40/00 (20060101); F25B
027/00 (); F25B 013/00 () |
Field of
Search: |
;62/238.6,323.1,243,114,430,434 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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195 13 710 |
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Oct 1995 |
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DE |
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195 00 445 |
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Jul 1996 |
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DE |
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195 00 445 |
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Jul 1996 |
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DE |
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0 256 305 |
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Feb 1988 |
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EP |
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0 960 755 |
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Dec 1999 |
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EP |
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1 057 669 |
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Dec 2000 |
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EP |
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2 772 426 |
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Jun 1999 |
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FR |
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Primary Examiner: Doerrler; William C.
Attorney, Agent or Firm: Striker; Michael J.
Claims
What is claimed is:
1. An apparatus for cooling, having a loop (60) for carrying a
refrigerant, a first heat exchanger (10) for outputting heat to a
heat reservoir (12), a second heat exchanger (114) for extracting
heat from a chamber (116) to be cooled, a compressor (18) and an
expansion device (120), characterized in that a first further heat
exchanger (70) is provided, which enables a heat transfer between
the loop (60) carrying the refrigerant and a coolant loop (80),
wherein the compressor (18) is operated directly electrically by a
starter/generator (72), a second further heat exchanger is provided
between the coolant loop and a motor oil, and a motor oil pump is
provided in a motor oil loop.
2. The apparatus of claim 1, wherein the first further heat
exchanger (70) is disposed downstream of the compressor (18) in the
loop (60) carrying the refrigerant.
3. The apparatus of claim 1, wherein a water pump (74) of the
coolant loop (80) can be operated directly electrically by a
starter/generator (72) or a battery.
4. The apparatus of claim 1, wherein the first heat exchanger (10)
includes a gas cooler.
5. The apparatus of claim 1, wherein CO.sub.2 is provided as the
refrigerant.
6. The apparatus of claim 1, wherein a reversible valve (76) is
provided, which can reroute the coolant loop to avoid additional
heat flows.
7. The apparatus of claim 1, wherein an inner heat exchanger (28)
is provided between the first heat exchanger (10) and the second
heat exchanger (114).
8. A method for cooling by means of an apparatus having a loop (60)
carrying a refrigerant, a first heat exchanger (10) for outputting
heat to a heat reservoir (12), a second heat exchanger (114) for
extracting heat from a chamber (116) to be cooled, a compressor
(18) and an expansion device (12), having the following steps:
driving the compressor (18), and conducting the refrigerant through
the loop (60) carrying the refrigerant, characterized in that the
refrigerant is conducted through a first further heat exchanger
(70), in which heat is transferred between the loop (60) carrying
the refrigerant and a coolant loop (80), wherein the compressor
(18) is operated directly electrically by a starter/generator (72),
a coolant loop in the coolant loop is conducted through a second
further heat exchanger, in which a heat exchange with a motor oil
takes place, and the motor oil is pumped through the second further
heat exchanger by a motor oil pump.
9. The method of claim 8, wherein a water pump (74) of the coolant
loop (80) is operated directly electrically by a starter/generator
(72) or a battery.
10. The method of claim 8, wherein CO.sub.2 is used as the
refrigerant.
11. The method of claim 8, wherein a reversible valve is used,
which reroutes the coolant loop to avoid additional heat flows.
12. The method of claim 8, wherein an inner heat exchanger (28) is
used between the first heat exchanger (10) and the second heat
exchanger (114).
Description
The invention relates to an apparatus for cooling, having a loop
carrying a refrigerant, a first heat exchanger for outputting heat
to a heat reservoir, a second heat exchanger for extracting heat
from a chamber to be cooled, a compressor and an expansion device.
The invention also relates to a method for cooling, by means of an
apparatus for cooling, having a loop carrying a refrigerant, a
first heat exchanger for outputting heat to a heat reservoir, a
second heat exchanger for extracting heat from a chamber to be
cooled, a compressor and an expansion device, having the steps of
operating the compressor and conducting the refrigerant through the
loop carrying the refrigerant.
PRIOR ART
Apparatuses and methods of the above generic type are used
particularly for climate control in vehicle passenger
compartments.
FIG. 3 schematically shows an air conditioner circuit. A first
medium enters a first heat exchanger 110 and flows through a loop
160. The medium gives up heat to the ambient air 162 and thus cools
itself down. A cooled medium emerges from the heat exchanger 110.
This cooled medium is now conducted through an inner heat exchanger
128, whose function will be explained hereinafter. After the medium
has emerged from the inner heat exchanger 128, it enters an
expansion device 120. The medium cools down sharply from expansion
and is then delivered to a second heat exchanger 114. In this heat
exchanger 114, the cold medium can cool down warm ambient air or
circulating air and made available, in the form of cold air 164, to
a chamber to be cooled, such as the motor vehicle interior. In this
process, the development of condensate 166 occurs. The medium, now
evaporated and possibly heated by the heat exchange in the heat
exchanger 114, emerges from the heat exchanger 114 and then flows
again through the inner heat exchanger 128. After emerging from the
inner heat exchanger 128, the medium enters a compressor 118, where
it is heated by compression. Thus a heated medium is again
available, which can enter a first heat exchanger 110 for heat
exchange. The loop is closed.
The inner heat exchanger 128 serves to increase the power in the
loop. Before entering the expansion device 120, the medium is
cooled by the returning medium, which has emerged from the second
heat exchanger 114 and is heated in reflux. Higher temperature
differences and hence an increase in the efficiency in the loop can
thus be achieved.
As the medium in the coolant loop, CO.sub.2 is gaining in
significance. The interest in this natural refrigerant is
increasing, given the rules and regulations requiring that the use
of CFCs be stopped.
Compared to conventional refrigerants, CO.sub.2 has a lower
critical temperature of 31.1.degree. C. Above this temperature,
liquefaction from a pressure increase is no longer possible. At
medium and high ambient temperatures, the heat output therefore
occurs at a so-called supercritical pressure, that is, a pressure
that for CO.sub.2 is above 73.8 bar. At supercritical pressure, the
heat output does not occur by condensation, as in the conventional
refrigerants, which occurs at a virtually constant temperature;
instead, the pressure and temperature are independent of one
another. Gas cooling takes place. However, the states in the
evaporator continue to be subcritical. Another notable feature of
the behavior of CO.sub.2 is that temperatures of about 140 to
150.degree. C. are already attained in idling.
ADVANTAGES OF THE INVENTION
The invention improves upon the generic apparatus in that a first
further heat exchanger is provided, which enables a heat transfer
between the loop carrying the refrigerant and a coolant loop. The
refrigerant, which can quickly be imparted a high temperature, is
thus capable of heating the vehicle coolant. This has numerous
advantages. It is already known, to enhance comfort, for the
vehicle to be air-conditioned several minutes before a trip begins.
For a heated passenger compartment, the air conditioner compressor
is operated, so that the refrigerant is compressed. Because once
the refrigerant has been compressed before being introduced into
the first heat exchanger it is carried into the first further heat
exchanger, the coolant can be preheated. In this way, the
temperature of the coolant is already at operating temperature even
before the internal combustion engine is started. By means of the
first further heat exchanger, it is likewise possible for the water
located in the radiator to be used at high pressure to cool the
refrigerant as needed.
Preferably, the first further heat exchanger is disposed downstream
of the compressor in the loop carrying the refrigerant. In this
way, the refrigerant is introduced at high temperature into the
heat exchanger, so that rapid heating of the coolant in the coolant
loop can occur.
It is preferred that the compressor can be operated by a
starter/generator or a battery. This starter/generator, which is
disconnected from the drive shaft of the engine via a clutch, can
thus furnish both the energy for pre-air-conditioning and the
energy for heating the coolant before the engine is started.
It is also advantageous that a water pump of the coolant loop can
be operated by a starter/generator or a battery. The coolant is
thus pumped through the heat exchanger because of the work of the
starter/generator.
It is especially advantageous if the first heat exchanger includes
a gas cooler. In this way, a heat exchange in the first heat
exchanger is not brought about by condensation, as in the
conventional refrigerants. Instead, a heat exchange in the gas
takes place.
It is especially advantageous if CO.sub.2 is provided as the
refrigerant. With CO.sub.2, the advantages of the invention can be
employed especially well, since the CO.sub.2 can be compressed by
the compressor to pressures of 100 to 150 bar, using the
starter/generator, making it possible to attain temperatures
between 140 and 180.degree. C. Rapid heating of the coolant in the
coolant loop thus occurs.
It is equally advantageous if a second further heat exchanger is
provided between the coolant loop and the motor oil. In this way,
the motor oil can be brought to an elevated temperature as well
before the engine is started.
In this connection, it can be especially advantageous that a motor
oil pump, which can be operated by a starter/generator or a
battery, is provided in the motor oil loop. Because of this
circumstance, not only the compressor and the water pump but the
motor oil pump can also be operated by the starter/generator. It is
equally conceivable for a heat exchanger to be placed in the oil
sump, that is, in the region of the oil pan, which heat exchanger
has coolant flowing through it, so that the heat from the
refrigerant is output to the motor oil via the engine coolant. As a
heat exchanger, the heat exchanger present in Diesel vehicles
between the coolant and the oil can also be used.
There are particular advantages if a third further heat exchanger
is provided between the coolant loop and the gear lubricant oil.
Thus the gear lubricant oil as well can be brought to temperatures
near operating temperatures before the vehicle is put into
operation.
It is especially useful if a reversible valve is provided, which
can reroute the coolant loop to avoid additional heat flows. This
function is useful if no additional heat flows in the coolant
during engine operation are wanted. In principle, however, the heat
exchanger can also be operated without valves, since the coolant
temperatures are below 120.degree. C. The additional heat quantity
that is output to the engine coolant by the loop carrying the
refrigerant can be output to the ambient air via the coolant heat
exchanger. The surface area of the coolant heat exchanger need not
be increased for this purpose, since the heat is produced at a
higher temperature level. The surface area of the gas cooler for
cooling the refrigerant, however, can be reduced, since some of the
heat is already output to the coolant before entering the gas
cooler.
It is especially advantageous that an inner heat exchanger is
provided between the first heat exchanger and the second heat
exchanger. An inner heat exchanger of this kind serves to increase
the power of the air conditioner. The refrigerant is precooled by
returning refrigerant before the expansion in the expansion device.
The returning refrigerant is likewise precooled, prior to
compression in the compressor, by the arriving refrigerant.
The invention improves on the generic method in that the
refrigerant is conducted through a first further heat exchanger, in
which heat is transferred between the loop carrying the refrigerant
and a coolant loop. In this way, the advantages of the apparatus of
the invention are applied to the method as well.
It is especially advantageous if the compressor is operated by a
starter/generator or a battery. This starter/generator, which is
disconnected from the drive shaft of the engine via a clutch, can
thus furnish both the energy for pre-air-conditioning and the
energy for heating the coolant before the engine is started.
Preferably, it is also advantageous that a water pump of the
coolant loop can be operated by a starter/generator or a battery.
The coolant is thus pumped through the heat exchanger because of
the work of the starter/generator.
It is useful if CO.sub.2 is used as the refrigerant. With CO.sub.2,
the advantages of the invention can be employed especially well,
since the CO.sub.2 can be compressed by the compressor to pressures
of 100 to 150 bar, using the starter/generator, making it possible
to attain temperatures between 140 and 180.degree. C. Rapid heating
of the coolant in the coolant loop thus occurs.
Especially advantageously, the coolant in the coolant loop is
conducted through a second further heat exchanger, in which a heat
exchange with the motor oil takes place. In this way, the motor oil
can also be brought to an elevated temperature before the engine is
started.
It is also useful that motor oil is pumped through the second
further heat exchanger by a motor oil pump, and that the motor oil
pump is operated by a starter/generator or a battery. Because of
this circumstance, not only the compressor and the water pump but
the motor oil pump can also be operated by the starter/generator.
It is equally conceivable for a heat exchanger to be placed in the
oil sump, that is, in the region of the oil pan, which heat
exchanger has coolant flowing through it, so that the heat from the
refrigerant is output to the motor oil via the engine coolant. As a
heat exchanger, the heat exchanger present in Diesel vehicles
between the coolant and the oil can also be used.
It is preferred if the coolant in the coolant loop is conducted
through a third further heat exchanger, in which a heat exchange
with the gear lubricant oil takes place. Thus the gear lubricant
oil as well can be brought to temperatures near operating
temperatures before the vehicle is put into operation.
It is especially advantageous if a reversible valve is used, which
reroutes the coolant loop to avoid additional heat flows. This
function is useful if no additional heat flows in the coolant
during engine operation are wanted. In principle, however, the heat
exchanger can also be operated without valves, since the coolant
temperatures are below 120.degree. C. The additional heat quantity
that is output to the engine coolant by the loop carrying the
refrigerant can be output to the ambient air via the coolant heat
exchanger. The surface area of the coolant heat exchanger need not
be increased for this purpose, since the heat is produced at a
higher temperature level. The surface area of the gas cooler for
cooling the refrigerant, however, can be reduced, since some of the
heat is already output to the coolant before entering the gas
cooler.
The method is furthermore advantageously refined in that an inner
heat exchanger is used between the first heat exchanger and the
second heat exchanger. An inner heat exchanger of this kind serves
to increase the power of the air conditioner. The refrigerant is
precooled by returning refrigerant before the expansion in the
expansion device. The returning refrigerant is likewise precooled,
prior to the compression in the compressor, by the arriving
refrigerant.
The invention is based on the recognition that especially in air
conditioners that use CO.sub.2 as the refrigerant, an advantageous
preheating of the coolant can be done. To that end, an additional
heat exchanger is provided, and the preheating of the coolant can
in particular be done along with the pre-air-conditioning of the
passenger compartment of the vehicle.
DRAWINGS
The invention will now be described in examples in terms of
preferred embodiments in conjunction with the accompanying
drawings.
Shown are:
FIG. 1, a schematic fragmentary view of an apparatus of the
invention;
FIG. 2, a state diagram, for explaining courses of events in an
apparatus of the invention; and
FIG. 3, a schematic illustration of an apparatus in the prior
art.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
FIG. 1 shows part of an apparatus according to the invention. The
part not shown to the right of the dot-dashed line, that is, to the
right of the inner heat exchanger 28, corresponds to the apparatus
that is shown in FIG. 3 to the right of the inner heat exchanger
128 and has already been described in conjunction with the prior
art.
In FIG. 1, two loops are shown. First, the loop 60 of a refrigerant
for operating the air conditioner is shown. Second, a coolant loop
80 for cooling an internal combustion engine 90 is shown. The
refrigerant is compressed by a compressor 18. This compressor 18 is
operated by a starter/generator 72 before the engine 90 is started.
Before the compressed refrigerant enters the first heat exchanger
10 in order to output heat, the refrigerant enters the first
further heat exchanger 70. Coolant that is transported by the
coolant loop 80 enters this heat exchanger 70 as well. The water
pump 74 can also be operated by the starter/generator 72 or
electrically in some other way for the sake of transporting the
coolant. In this way, heat is output to the coolant, so that its
temperature can reach ranges near those of operation. With the
valve 76, during normal operation of the engine 90, the production
of additional heat flows in the coolant can be prevented. However,
it is also possible to operate the system without the valve 76,
since the coolant remains below temperatures in the range of
120.degree. C. The additional heat quantity that through the loop
60 and the first further heat exchanger 70 enters the coolant loop
can be output to the ambient air via the coolant heat exchanger 78.
The area of the coolant heat exchanger 78 need not be increased for
that purpose, since the heat occurs at a higher temperature level.
The area of the first heat exchanger 10, designed as a gas cooler,
can be reduced, however, since some of the heat has already been
output to the coolant before entry into the gas cooler.
FIG. 2 is a thermodynamic state diagram for CO.sub.2 in which the
pressure p is plotted over the specific enthalpy h. Isotherms are
also shown in the graph, with the associated temperatures indicated
at the upper edge of the graph. The isotherms are shown at
intervals of 10.degree. C. The isotherm is also shown at
31.1.degree. C., which is the critical temperature of CO.sub.2.
Three different cycles are plotted in the state diagram of FIG. 2.
The cycle marked by blank circles is equivalent to an idling mode.
The cycle represented by blank triangles is equivalent to driving
at 22 km/h. The cycle marked by blank squares corresponds to
driving at 64 km/h.
The diagram will now be explained, beginning at a bottom right-hand
corner of an arbitrary one of the cycles. First, compression takes
place, which raises the temperature of the medium. Such a
compression can be caused for instance by the compressor 18 of FIG.
1. The medium thus enters a state of high temperature at high
pressure, and once again the enthalpy is increased. Beginning at
the upper right-hand corner of the cycles, the thermal energy is
now output essentially isobarically. This output of thermal energy
takes place in all cycles essentially above the critical
temperature of CO.sub.2 ; that is, gas cooling takes place. The
range of gas cooling is marked by the double arrow A. The system
reaches states corresponding to the upper left-hand corner of the
cycles, that is, states of reduced enthalpy and reduced
temperature. An expansion thereupon occurs, so that both the
temperature and the pressure vary, with essentially unchanged
enthalpy. The lower left-hand point of the cycles is now reached.
In these states, the CO.sub.2 is partially liquefied. This is
possible since the temperature is subcritical. The events caused by
the exceeding of the critical temperature limit are called
"transcritical". Next, the refrigerant absorbs heat, so that
without a pressure change, the lower right-hand point of the
various cycles is reached. The cycles are thus completed.
The above description of the exemplary embodiments of the present
invention is meant solely for illustrative purposes and not for the
sake of limiting the invention. Various changes and modifications
can also be made within the scope of the invention without
departing from the scope of the invention or its equivalents.
* * * * *